Control device for radio receivers



Filed May 25, 1934 Patented Mar. 23, 1937 PATENT OFFICE ooN'rnoLDEvIoE FOR RADIO RECEIVERS Hans Wiinning, Berlin,

Telefunken Gesellschaft. fiir Germany, assignor to Drahtlose Tele- I graphic, in. b. FL, Berlin, Germany, a corporation of Germany Application May 25, 1934, Serial No. 727,380 In Germany May 30, 1933 Claims.

An object of this invention is to provide a control device for a radio apparatus or receiver whereby the power supply of the receiver may be switched on and off by a control means which also serves to change over one or more oscillatory circuits of the set for reception on a different wave length.

A further object of the invention is to provide a series of cams on a single control shaft so arranged that one of them serves to turn the power supply of the set on or off while the other cams change the inductance values of oscillatory cir-- cuits of the receiver.

In such switching arrangements there is a danger of the contacts of the receiver input circuits being capacitively coupled with similar contacts located in their vicinity and serving for the supply of the main or line voltage. According to the present invention disturbances and difliculties so caused are obviated by using a switch control of the greatest length possible within a receiver of given size. This is arranged with reference to the uni-control shaft in such a way that the contact points of the line supply switch 5 are removed as far as feasible from the contacts of the wave-change switch or switches or the contacts which change the set to the playing of phonograph records.

For a better understanding of the invention 0 reference is made to the attached drawing, in

which,

Fig. 1 is a view of the control mechanism showing also diagrammatically the power transformer and tuned circuits of the receiver.

Fig. 2 is a cross sectional view through the control shaft of Fig. l.

A radio receiver denoted by R has power supplied to its several circuits through power supply terminals l, power supply transformer 0. having iron core 3 and whose primary 4 is connected to the alternating current mains M through the movable switch contacts I). The transformer a and contacts b are located near one small end of the rectangular cabinet 2 and near the opposite end is mounted the control shaft c provided with the operating knob d. Shaft c has secured thereto the cams 5, 6 and l, cam 5 cooperating with one end of a rod 1 the other end of which is connected to the contacts or blades 1). Cams 6 and 50 I serve for changing the wave length of the resonant circuits 8 and 9 which are component parts of the receiver. As shown in more detail in Fig. 2 each coil II is mounted within a metallic coil pot l5 secured to a mounting plate or board it 5 provided with openings l2. Below these openings the cams 6 and l cooperate therethrough with spring or flexible switch blades l3 which engage contacts l4. One end of coils II is connected to one end of blades I3 while intermediate taps of coils H are connected respectively to the fixed contacts M. It will thus be seen that when shaft 0 is rotated the power supply of the receiver is first turned on by switch blades 17 and upon rotating it further, the wave length of the resonant circuits may be changed when cams 6 and I raise the blades l3. It will thus be seen that by placing the component parts in the relative positions in the receiver shown in Fig. 1, the switch contacts b for establishing connection or disconnection of the supply mains are disposed at a great distance from the other switch contacts l3, l4.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a radio receiver, the combination of a power supply transformer, a switch arranged to connect the primary of said transformer to power supply mains, a control shaft, a cam secured to said shaft, operating connections between said switch and said cam, at least one resonant circuit, a second switch having its terminals connected to spaced apart points of said circuit, and a second cam secured to said shaft and arranged to actuate said second named switch said transformer being located at such a remote distance from said second switch as to prevent energy transfer thereto when said transformer is energized.

2. In a radio receiver, the combination of a power supply device, a switch arranged to connect said device to power supply mains, a control shaft, means connected to said control shaft and arranged to actuate said switch, a plurality of resonant circuits each comprising a coil and a condenser, a separate metallic shield surrounding each of said resonant circuits, a connection between an intermediate point and one end of said coils including movable switch blades and a plurality of cams mounted on said control shaft and arranged to actuate said switch blades.

3. In a device of the class described, the combination of a rectangular shaped cabinet, a power supply switch for said device located near one small end of said cabinet, a control shaft located near the opposite end of said cabinet, means connected to said control shaft and arranged to actuate said switch, at least one resonant cir-' cuit mounted in said cabinet, a metallic member arranged to shield said resonant circuit, a second switch located adjacent said shaft and having its terminals connected to spaced apart points of said resonant circuit and actuating means secured to said control shaft arranged to actuate said second named switch said second switch being located at such a remote distance from said power supply switch as to prevent energy transfer therebetween.

4. In a radio device, the combination of a support having an aperture therein, a metallic shield, a resonant circuit, a fixed switch contact and a movable switch contact mounted in said shield, and said resonant circuit comprising a coil and a condenser, leads connecting said respective switch contacts to spaced apart points on said coil and operating means comprising a shaft located exterior to said shield and a cam on said shaft arranged to project through said aperture and operate said movable switch contact.

5. In a radio device, the combination of an alternating current power supply device, a switch arranged to connect said device to alternating current mains, a plurality of resonant circuits each comprising a coil and a condenser, metallic shielding means surrounding each of said resonant circuits, a connection between one end and an intermediate point of each of said coils including movable switch blades, a shaft, a cam on said shaft arranged to operate said first named switch upon a predetermined amount of rotation of said shaft in one direction and other cams on said shaft arranged to actuate said movable switch blades respectively upon a further rotation of said shaft in the same direction.

HANS WI'I'INNING. 

